The earliest symptom of retinitis pigmentosa (RP) is an electroretinogram (ERG) characterized by an unusually prolonged time-course. This abnormality manifests itself before the disease has progressed to a stage in which the patient's visual sensitivity is adversely affected, or before it is possible to see any retinal changes with the ophthalmoscope. It is likely that psychophysically measureable changes in the temporal resolution of the visual system accompany this change in the ERG record. It is proposed to explore this possibility by designing and validating a series of psychophysical tests which measure the visual system's responsiveness to temporal changes. These include measurements of temporal contrast sensitivity, temporal brightness maximization, visual reaction time, and critical duration. The tests will be validated on a group of previously diagnosed RP patients, a group of relatively high-risk subjects selected from the student body at the National Technical Institute for the Deaf (NTID) in Rochester, New York, and a group of normal controls. If, as expected, the results of these tests correlate well with accompanying ERG data, they will provide the basis for a routine screening device for those at risk of RP. Psychophysical measurements offer several advantages over ERG measurements as a screening technique, including low cost, ease of administration, and patient comfort. It is proposed to incorporate the tests into a self-contained automated system under the control of an inexpensive programmable microprocessor. This would make it possible to provide built-in controls for non-visual response factors, and would eliminate the possibility of experimenter bias. Use of such a device would allow routine screening of large numbers of persons, thereby greatly increasing the opportunity for early detection of potential RP patients.